This invention relates to a one-shot process for the preparation of polyamines containing primary amino groups and a process for producing polyurethanes (ureas) therefrom.
It is known that isocyanates may be converted into amines by acid or basic catalysis, as disclosed e.g. in The Organic Chemistry of Nitrogen by N. V. Sidgwick, Clarendon Press, Oxford, page 236 (1966) and in Advanced Organic Chemistry: Reactions, Mechanisms and Structure, by J. March, McGraw-Hill Book Co., New York, page 658, (1968). Sidgwick mentions the possibility of alkaline hydrolysis of the isocyanate groups but only in general terms without specific details.
Both multistage hydrolysis processes (DE-A No. 2,948,419, DE-AS No. 3,039,600 and DE-OS No. 3,131,252) and single stage hydrolysis processes (No. 3,223,400/EP No. 97,299, DE-OS No. 3,223,398/EP No. 97,298 and DE-OS No. 3,223,397/EP No. 97,290) have been proposed. In the one-stage process disclosed in DE-OS No. 3,223,400, so-called "ethereal solvents" are used together with tertiary amines as catalysts. In the process disclosed in DE-OS No. 3,223,398, polar solvents such as dimethylformamide are used together with tertiary amines or relatively large quantities of alkali metal hydroxides, alkali metal silicates or alkali metal cyanides as catalysts. Polar solvents are used together with carbonates or carboxylates as catalysts in the process disclosed in DE-OS No. 3,223,397.
All of the known processes for the preparation of polyamines are more or less complicated. Even the known single stage processes could be further simplified. It would be desirable to have a simpler process which would enable more economic production of polyamines with even better conversion rates of NCO/NH.sub.2 (i.e. higher NH.sub.2 numbers) by a smoother reaction. For example, conventional processes could be improved so that: (1) no filtration is required; (2) no distillative separation of a tert.-amine catalyst is required; (3) the quantity of catalyst required could be reduced to a level such that the catalyst could be left in the polyamine; (4) quantitative conversion of NCO into NH.sub.2 groups (high conversion rate of NCO/NH.sub.2, i.e. high amine numbers, close to the theoretical value) is achieved; (5) formation of by-products which must be removed is avoided; and (6) working up of the polyamines and auxiliary substances may be done by a simple method.